Effect of Flash Glucose Monitoring on Glycemic Control

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Northerner

Northerner

Admin (Retired)
Relationship to Diabetes
Type 1
OBJECTIVE The FreeStyle Libre (FSL) flash glucose-monitoring device was made available on the U.K. National Health Service (NHS) drug tariff in 2017. This study aims to explore the U.K. real-world experience of FSL and the impact on glycemic control, hypoglycemia, diabetes-related distress, and hospital admissions.

RESEARCH DESIGN AND METHODS Clinicians from 102 NHS hospitals in the U.K. submitted FSL user data, collected during routine clinical care, to a secure web-based tool held within the NHS N3 network. The t and Mann-Whitney U tests were used to compare the baseline and follow-up HbA1c and other baseline demographic characteristics. Linear regression analysis was used to identify predictors of change in HbA1c following the use of FSL. Within-person variations of HbA1c were calculated using
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RESULTS Data were available for 10,370 FSL users (97% with type 1 diabetes), age 38.0 (±18.8) years, 51% female, diabetes duration 16.0 (±49.9) years, and BMI of 25.2 (±16.5) kg/m2 (mean [±SD]). FSL users demonstrated a −5.2 mmol/mol change in HbA1c, reducing from 67.5 (±20.9) mmol/mol (8.3%) at baseline to 62.3 (±18.5) mmol/mol (7.8%) after 7.5 (interquartile range 3.4–7.8) months of follow-up (n = 3,182) (P < 0.0001). HbA1c reduction was greater in those with initial HbA1c ≥69.5 mmol/mol (>8.5%), reducing from 85.5 (±16.1) mmol/mol (10%) to 73.1 (±15.8) mmol/mol (8.8%) (P < 0.0001). The baseline Gold score (score for hypoglycemic unawareness) was 2.7 (±1.8) and reduced to 2.4 (±1.7) (P < 0.0001) at follow-up. A total of 53% of those with a Gold score of ≥4 at baseline had a score <4 at follow-up. FSL use was also associated with a reduction in diabetes distress (P < 0.0001). FSL use was associated with a significant reduction in paramedic callouts and hospital admissions due to hypoglycemia and hyperglycemia/diabetic ketoacidosis.

CONCLUSIONS We show that the use of FSL was associated with significantly improved glycemic control and hypoglycemia awareness and a reduction in hospital admissions.

Full report:
care.diabetesjournals.org

Effect of Flash Glucose Monitoring on Glycemic Control, Hypoglycemia, Diabetes-Related Distress, and Resource Utilization in the Association of British Clinical Diabetologists (ABCD) Nationwide Audit

OBJECTIVE. The FreeStyle Libre (FSL) flash glucose-monitoring device was made available on the U.K. National Health Service (NHS) drug tariff in 2017. This stud
care.diabetesjournals.org care.diabetesjournals.org
 
Good to see a study based on such a large data set.
It also includes a recognition of the different starting points for participants.

I hope that it can lead to the Libre being more readily available on the NHS.
 
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My question would be how accurate are the sensors. Have there been studies on the correlation of predicted HbA1c and a lab test.
I experience difference in CGM readings and fingerpricking.
 
JohnP21 said:
My question would be how accurate are the sensors. Have there been studies on the correlation of predicted HbA1c and a lab test.
I experience difference in CGM readings and fingerpricking.
Click to expand...
that varies from person to person thoughh and sensor to sensor, my current one is pretty much spot on

Ive only had one hba1c since having the Libre and predicted from that and labs were bang on with eachother, for others it isnt xx
 
JohnP21 said:
My question would be how accurate are the sensors. Have there been studies on the correlation of predicted HbA1c and a lab test.
I experience difference in CGM readings and fingerpricking.
Click to expand...
I am a Type 2 I have been using a Freestyle Libre for over a year, I have had at least 3 HBA1C over that period, they have all predicted it to be lower by at least 4 points. I was not totally surprised as I use the mySugr app and it always gave a lower estimated HBA1C too! Some find it is spot on!
 
JohnP21 said:
My question would be how accurate are the sensors. Have there been studies on the correlation of predicted HbA1c and a lab test.
Click to expand...

Here's one (in children, but only 24 children). They find the estimated HbA1c is usually a little lower but the differences are pretty small (so the estimate is pretty accurate).

Accuracy of Glucose Sensor Estimate of HbA1c in Children with Type 1 Diabetes | ESPE2019 | 58th Annual ESPE (ESPE 2019) | ESPE Abstracts

abstracts.eurospe.org abstracts.eurospe.org
 
JohnP21 said:
My question would be how accurate are the sensors. Have there been studies on the correlation of predicted HbA1c and a lab test.
Click to expand...

I think part of the importance of trials like this is that they show that even though we know these things aren't quite as good as our meters (though they're pretty good and our meters aren't that accurate either), following them allows for better control.

So while my sensor might be reading 0.5 low this week and the next one 0.7 high (on average), if I just stick to trying to keep TIR good (as reported by these flawed devices) that's a sound strategy.
 
I didn't even realise Libre had a predicted HbA1c until recently but, too be honest, I don't really care.
I use it to maximise my time in range.
My HbA1c has always been pretty good but I know I have "achieved" this through too many hypos. The Libre allows me to predict and react to hypos before they happen.
 
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I'm only on the second sensor but so far it doesn't bear all that much resemblance to my BG other than the direction of the arrows. Apparently today I was hypo from before I went to bed until about 10am this morning - I wasn't. Both have said I'm hypo when I'm not according to my BG meter - which yes I know all about BG meter accuracy but the results on that meter have always been reflected in my HbA1c results hence I believe the meter. As the pump and meter communicate with Bluetooth and the Libre doesn't - it's got some reputation to live up to in my book.

So far it's no more accurate than the one I trialled soon after it was first released.

We'll have to see .......
 
helli said:
I didn't even realise Libre had a predicted HbA1c until recently but, too be honest, I don't really care.
Click to expand...

I agree. Feels like something that some people are excited by but I don't see the value. I prefer to see things that show changes in the short term. HbA1c changes too slowly to be helpful as a feedback measure.
 
I have just started to use my phone as a reader aswell , the estimated HBAC1 on my Libre Link (phone) and Libre Veiw(Lap top), are 4 points out . My time in target is 89 % in both?
 
Bruce Stephens said:
I agree. Feels like something that some people are excited by but I don't see the value. I prefer to see things that show changes in the short term. HbA1c changes too slowly to be helpful as a feedback measure.
Click to expand...
For those of us with the privilege of CGMs or Libre, TIR seems to be the best indication.
However, this is not possible for everyone (or even the majority) and the Hb1Ac test is simple so I suspect it is what will remain the default measure of control for some time.
I think I was surprised the study emphasised Hb1Ac improvements when it relied on Libre. Maybe it was the only thing that could be used as a pre-sensor baseline?
(Sorry, I think I answered my own question and am now just rambling/avoiding work 🙂 )
 
Well only on my second sensor, so not even a full 4 weeks let alone a calendar yet. The range was set by the DSN to being with at 3.9 -10.0 and I'm usually well within that, as it reads well over 1.0 out in the 'normal' range though less than 1.0 at under 4 so most of the 7% hypo it shows on the bar graph, have actually been hypos. (and the highs haven't been quite that high in the main either) However - I would like to tackle the time I spend 'under 4.5 ish' and even more the 'above 8 ish' since with an A1c in the low 50s (53 or 54) there's room for improvement, though nobody at my clinic has pressed me about that for quite a while and IMHO I'm hardly likely to become obsessive about it anyway as that's never been a personal trait AFAIK.

Q1. Is there anything that can narrow the variance - I'm usually as well hydrated as I want to be (haven't a clue though clinically though it's fair to say certain bits of my waterworks aren't working as well as they used to - and TMI probably - sometimes I have to deliberately try not to cough etc on the way to the loo, so in the middle of the night I ALWAYS need to get out of bed immediately however cold it is) but don't know if there's anything else I might consider?

Q2. What would people suggest I amend the 'range' to, in order to try and specifically highlight the areas I need to? Do I try and do them separately one at a time?
 
I asked the question originally as over the last year on the sensors, I had noticed the sensors gave average readings of up to 2mmol/L lower than finger prick results. However recently I have had two sensors give readings nearer to the BG readings. Then the next reverted back to the 1-2mmol/L lower difference. That sensor came off early and the current one is the most accurate I have ever had.
Just shows the differences in sensors. If you have a sensor reading lower your “time in range“ will be distorted too.
Time will if it is a batch phenomenon or sensors become more accurate. But if it is patient dependant who knows.
Another observation is that prior to the Librelink app being updated recently, my freestyle reader and phone app gave identical readings. Since the upgrade (to improve accuracy) there is a small difference in readings.
The main advantage I find are the graphs showing my response to different foods and insulin bolus. and also how my basal rate is performing.
 
Libre are "factory calibrated". Unfortunately, I find the factory calibration to be out from my finger pricks most of the time but found there are alternative phone apps which can read the sensors. Abbott do not share the algorithm they used to convert interstitial fluid numbers to blood glucose numbers so these apps use slightly different algorithms. The advantage for me is that these different algorithms allow you to calibrate against finger prick. As I result my Libre readings are closer to finger pricks and I have more confidence in them.
I have an Android phone. I used to use Glimp but now use xDrip+.
The disadvantage is that these cannot be automatically shared with my diabetes team. They are ok with that but some may be less accepting of non-standard use of Libre.
 
Some find it very temperamental. not surprising as they are essentially a foreign body.
 
They might be a foreign body, but the little tube that that is left in your body is completely medically inert. Your body won't recognise it as a foreign body. After all, we have been inserting plastic aortas into folk for decades without anybody rejecting the replacement. And all sorts of stents and catheters, to say nothing of the Venflon devices used for hospital drips.

So the system may be temperamental for some folk, but it isn't because it's a foreign body.
 
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